Loademwell;
I have closed my bolt on very tight loads due to neck sizing and have never had any trouble opening bolt before or after firing. The only time I had a bolt opening issue was when I had a extreme over pressure caused by my re sizing lube cementing the bullets into the cases on a batch that was a couple years on the self. I wasn't cleaning the lube out of case necks after I was Q tip ing necks with RCBS case lube., anyway, if I had your rifle in my hands I would make up a few dummy rounds and feel very carefully how the bolt handle feels closing. I am thinking you have a shoulder or indent in the locking lugs from some previouse issue or birth defect of the rifle, if you will.
If you have trouble opening the bolt handle with a dummy load chambered I guess you might bump the bolt forward with a soft block of some kind.
But in careful feeling of the bolt closing you should feel something.

thanks! I bet that was the problem I was having. My mentor (who is an old school reloader) wasn't advised that I had neck sized die's. or didn't understand it yet. He told me "Always use lube on your casing" Even when I questioned him about the "lubeless dies" he replied; "Don't know nothing about them, but I'm sure it wouldn't hurt anything."
So all in all, I bet that was the prob. While letting the live round sit in the gun for a while, the lube fused inside of the chamber. Shooting it off must have jolted it free.
Lessons learned, Clean all finished rounds off before you load them up.